Email:
cmueller@usgs.gov
Office Phone:
303-273-8559
ORCID:
0000-0002-1868-9710
Location
USGS
, PO BOX 25046 MS 966 DFC
DENVER
CO 80225
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This data set represents the results of calculations of hazard curves for a grid of points with a spacing of 0.05 degrees in latitude and longitude. This particular data set is for horizontal spectral response acceleration for 0.2-second period with a 1 percent probability of exceedance in 1 year. The data are for the Western United States and are based on the long-term 2014 National Seismic Hazard Model.
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These data sets are the results of calculations of hazard curves for a grid of points with a spacing of 0.05 degrees in latitude and longitude. They represent the chance of experiencing potentially damaging ground shaking for fixed ground shaking levels that corresponds with MMI = VII. The values are obtained by averaging the probability of experiencing MMI = VII based on a peak ground acceleration value of 0.2152 g for site class D, and the probability of experiencing MMI = VII based on 1.0-second spectral acceleration value of 0.2256 g for site class D. The data are for the Central and Eastern United States.
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A comparison of the 2017 USGS South America seismic hazard model with the Global Seismic Hazard Assessment Program (GSHAP) model and the 2010 USGS preliminary model was made to see how the models differ. The comparisons were made as ratios of PGA at 10% probability of exceedance in 50 years. Ratio maps of each comparison are included as a geo-referenced tiff (GeoTIFF).
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The U.S. Geological Survey (USGS) national seismic hazard models (NSHM) consider two kinds of earthquake sources. Specific faults are modeled where possible. Where faults cannot be identified or characterized, alternative sources can be developed from seismicity catalogs. In a paper submitted to Seismological Research Letters ("Related External Resources", below), we describe a methodology that has been developed at the USGS for making earthquake catalogs for seismic hazard analysis. In this data release we provide the catalogs for the conterminous U.S. that accompany the SRL article. A new catalog is assembled from several preexisting catalogs. Moment magnitudes and related parameters for modeling seismicity...
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In processing step 3, declustering is applied to flag aftershocks and foreshocks in catalog wmm.c2. Each earthquake is considered a potential mainshock, and an algorithm searches for events within a specified distance from its epicenter and time after its origin (Gardner and Knopoff, 1974). A smaller earthquake found within a window is an aftershock. If a larger earthquake is found, the first earthquake is a foreshock of the larger one. WUS catalog wmm.c3 is produced by deleting aftershocks and foreshocks from wmm.c2; it consists of statistically independent earthquakes with moment magnitudes greater than or equal to 2.5.
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